Liquid chromatography has been known in the art as a process for determining the composition of various materials for several years. Using this procedure, a test material is added to a liquid mobilizer and passed through a stationary liquid or solid phase material under extremely high pressures. The test material emanates from the solid phase material in a separated fashion such that the relative quantities of its component substances can be measured. The high pressure needed for liquid chromatography creates a need for precision instruments to control the pressure of the fluid flow.
The check valve assemblies used in liquid chromatography pumps must therefore be carefully monitored and often replaced to maintain the necessary precision required for their application. Additionally, filters are generally used with the valve assemblies, which filters must be replaced more often than the assemblies themselves.
Prior art valve assemblies used with liquid chromatograph pumps are generally made to be disassembled such that their component parts can be replaced when necessary. However, disassembly and replacement of the parts used with the assembly can be tedious, difficult and time consuming. Also, piecemeal replacement of valve assembly parts necessitates large inventories to ensure an adequate supply of each component of the assembly. The resulting cost is large.
Some prior art devices provide disposable assemblies, including disposable filters. Such devices are, however, inefficient inasmuch as it is usually necessary to replace the filter before replacement of the entire assembly is required. Since the filter comprises a small portion of the entire assembly, devices which propose disposal of the assembly at each instance when the filter needs replacement are expensive and, consequently, inefficient.
Also, in the field of liquid chromatography there are numerous manufacturers providing chromatographic equipment. The equipment of each manufacturer is generally not compatible with that of any other manufacturer. A typical user has numerous chromatographs provided by several different manufacturers. Accordingly, the typical user must further increase his inventory to maintain a separate supply of spare parts for each manufacturer's equipment. It is readily understood that since each manufacturer's valve assemblies are constructed differently, difficulty in replacing worn parts is increased due to the need to know the exact construction of valves for various manufacturers.
It is, therefore, desirable to provide a disposable valve assembly for a liquid chromatograph wherein the filter thereof can be replaced and the assembly reused until other components of the valve assembly must be replaced. It is further desirable to provide a valve assembly for a liquid chromatograph wherein the filter thereof may be quickly and easily replaced. It is additionally desirable to provide a valve assembly for a liquid chromatograph, which assembly is suitable for use with chromatographs made by various manufacturers.